Abstract: An x-ray apparatus and method are presented for controlling x-rays to analyze combinatorial libraries for the rapid screening of different materials and different conditions. The apparatus includes a laboratory x-ray source, one or more x-ray optics, a combinatorial library, and a detector such as an x-ray detector or an electron energy detector. The apparatus can be used to perform analytical measurements on individual members of the library, where the measurements may comprise x-ray fluorescence, x-ray diffraction, total reflection x-ray fluorescent spectrometry, and/or extended x-ray absorption fine structure.